1) Field of the Invention
The present invention relates to an on-off valve for use in high pressure gas vessels, More particularly, This invention relates to an on-off valve where the flow amount of gas is restricted when the valve is made off.
2) Prior Art
Accidents due to ignition in high pressure vessels sometime occur when oxide gas is removed from the gas vessels. The following are considered causes of such accidents: (1) An Oxide per se is an essential for ignition; (2) when a highly pressures gas flows into an airtightened space of an apparatus, which is connected to the outlet side of the operation valve of a high pressure vessel heat is instantaneously generated due to adiabatic compression; and (3) the sealing member or lubricant of the valve, or dust in the valve acts as an ignition material.
In order to prevent such accidents, cautions are known such that when opening the valve of such a high pressure vessels the operating handle should be slowly moved into the opening direction in order to decrease the gas pressure gradually in the space at the downstream side of the valve.
However, when using oxygen bombs for medical use, for example, it is necessary to supply oxygen to patients in an emergency, so that the operator cannot pay attention to the caution that the operation valve should be opened slowly.
Further, such oxygen bombs for medical uses are mostly equipped in ambulance cars or carried together with patients who are being brought to a hospital, therefore these bombs are so designed as to be made compact, taking transportation convenience into consideration. In such compact oxygen bombs, the operating valves are also made compact and the operating handles to turn the valve on or off are also small, making it difficult to grasp. Therefore, it is particularly difficult to rotate the handle slowly in the opening direction and to conduct a delicate operation by hand.